A police officer has been admitted to hospital after two police dogs he is believed to have cared for were found dead at the weekend. The dogs, a full-grown Belgian malinois and five-month-old alsatian puppy, were found dead after being locked in a car on one of the hottest days of the year.

The Metropolitan police would not confirm that the officer admitted to hospital was the dogs' handler Sergeant Ian Craven, an experienced dog trainer who may now faces charges for animal cruelty following the deaths of the animals.

The force did confirm that an on-duty officer had abruptly left his post on Sunday, the same day the dogs died, causing other officers to fear for his safety. He was found with hand injuries and taken into hospital. It is not known if the wounds were self-inflicted. "On Sunday 26 June at approximately 12.25hrs police were alerted to a police officer suddenly leaving his duty posting, causing concern for the officer's safety and welfare," police said in a statement.

A search was immediately launched, the statement added. "The officer was treated as a missing person and a search began, eventually locating him in Newham borough suffering a hand injury. He was taken to an east London hospital as a precaution. He is currently receiving medical treatment."

It also emerged that Craven was allegedly disciplined after the death of a police dog in July 2004. A police spokesman would not confirm the identity of the reprimanded officer, but said: "On 6 July 2004 a police dog died at the Metropolitan police dog training school. There was a full and thorough investigation which led to a male PC receiving a reprimand."

Craven is thought to have been a PC at the time, and has since been promoted to sergeant.

The Metropolitan police commissioner, Sir Paul Stephenson, said he was "very saddened" by the deaths of the two dogs.

"We are taking it very seriously," he said. "There's an investigation going on. It's being led by the RSPCA, with a separate internal disciplinary investigation going on in the force."

The dogs were found collapsed at 11am on Sunday in a locked and unventilated car at the force's training centre in Keston, Kent.

Officers at the scene desperately tried to save the lives of the animals, who were taken to an emergency vets, where both died.

The deaths follow those of two German shepherd police dogs, who were left to die in a car in extreme heat outside Nottinghamshire police headquarters in July 2009. Police dog handler PC Mark Johnson was handed a six-month conditional discharge after he was found guilty of animal cruelty.

A spokeswoman from the Dogs Trust, the UK's largest dog welfare charity, said it was "saddened" to hear of the two latest deaths.

She added: "Whilst the cause of death is still to be determined, the charity would like to remind dog owners and police dog handlers that leaving your dog in a car can prove rapidly fatal, particularly during a heatwave.

"It can take just 20 minutes for a dog to die and temperatures can reach over 40C in some vehicles."